A variety of medical devices are employed to monitor a health condition. For example, devices include those designed to enable a user to manage a health condition based at least in part on the level of analyte in the body. These types of devices include analyte determination devices, drug delivery devices, and the like.
Such analyte devices have become widely used in recent years for people with diabetes. Diabetics have typically measured their blood glucose level by lancing a finger tip or other body location (i.e., alternate site) to draw blood, applying the blood to a disposable test strip in a hand-held meter and allowing the meter and strip to perform an electrochemical test of the blood to determine the current glucose concentration. Such discrete or individual, in vitro tests are typically conducted at least several times per day. Detailed descriptions of such glucose monitoring systems and their use are provided in U.S. Pat. No. 7,058,437, issued to TheraSense, Inc., on Jun. 6, 2006, which is incorporated by reference herein in its entirety.
In vivo glucose monitoring devices are designed to provide continuous glucose monitoring. Some of these continuous systems employ a disposable, transcutaneous sensor that is inserted into the skin to measure glucose concentrations in interstitial fluid. A portion of the sensor protrudes from the skin and is coupled with a durable controller and transmitter unit that is attached to the skin with adhesive. A wireless handheld unit is used in combination with the skin-mounted transmitter and sensor to receive glucose readings periodically, such as once a minute. At a predetermined time interval, such as every three, five or seven days, the disposable sensor is removed and replaced with a fresh sensor which is again coupled to the reusable controller and transmitter unit. With this arrangement, a person with diabetes may continuously monitor their glucose level with the handheld unit. The handheld unit of the in vivo system can also include an in vitro test strip meter for conducting individual tests as described above. The in vitro test strip meter can be used to calibrate the continuous monitoring system each time a new in vivo sensor is implanted. Additionally, the in vitro test strip meter can be used as back up in case the in vivo system fails, a new sensor is equilibrating, or when the transmitter must be turned off, such as during takeoffs and landings when aboard an airliner. Detailed descriptions of such a continuous glucose monitoring system and its use are provided in U.S. Pat. No. 6,175,752, which is incorporated by reference herein in its entirety.
Drug delivery devices, including wholly implantable infusion pumps and pumps that infuse drug through a transcutaneously placed fluid channel such as flexible tubing, are devices that enable the controllable administration of a drug to a user. Pumps may be under the control or semi-control of a healthcare monitoring device or may be controlled by the user. Examples of such include insulin pumps used by diabetics to administer insulin for glucose control.
The purpose of in vitro or in vivo glucose monitoring, and insulin delivery devices, is to assist people with diabetes in keeping their blood glucose within a predetermined range. If a person's blood glucose level rises too high, hyperglycemia can occur. The short term effects of hyperglycemia can include fatigue, loss of cognitive ability, mood swings, excessive urination, excessive thirst and excessive hunger. Of more immediate concern, if a person's blood glucose level drops too low, hypoglycemia can occur. Like hyperglycemia, symptoms of hypoglycemia also include fatigue and loss of cognitive ability. If unchecked, however, hypoglycemia can quickly lead to loss of consciousness or coma. Some diabetics have little or no symptoms of hypoglycemia, or find it difficult to distinguish between symptoms of hyperglycemia and hypoglycemia. Long term effects of not keeping blood glucose levels within a proper range include health complications such as cardiovascular disease, chronic renal failure, retinal damage which can lead to blindness, nerve damage, impotence, and gangrene with risk of amputation of toes, feet, and even legs. Clearly, proper glucose monitoring and corrective action based on the monitoring is essential for people with diabetes to maintain their health.
Also of importance is compliance to a glucose monitoring regime. Compliance may be particularly difficult with persons who require supervision, e.g., young children or mentally impaired individuals. Compliance may include strict adherence to healthcare provider and/or caregiver provider instructions. If healthcare instructions change, it is necessary that the user be timely notified of such changes. Likewise, it is important that instructions be readily available in case a person needs to be reminded thereof.